A federal jury in Riverside ruled Thursday in favor of Mattel Inc. on several counts in a copyright infringement case that has pitted the El-Segundo based company against rival MGA Entertainment Inc.

In an unanimous decision, the 10-person jury found that the majority of the Bratz drawings, prototypes and sculpts were created by former Mattel designer Carter Bryant while he was employed by the Barbie maker.

The jury also found that Van Nuys-based MGA and its chief executive, Isaac Larian, interfered with the contractual relationship between Bryant and Mattel and aided Bryant’s breach of fiduciary duty that he owed to Mattel. While working at the company, Bryant signed an inventions agreement with Mattel that assigned all ownership of his designs, ideas and concepts to the company.

“This is a victory for all the hard-working people at Mattel who come together to create many of the most beloved toys for children,” said Mattel Chief Executive Robert Eckert in a statement. “It is also a victory for all those who believe in fair play.”

In the next phase of the trial, which is scheduled to begin shortly, the jury will determine if the Bratz dolls infringe on the Bratz drawings, which are now owned by Mattel. If the drawings do infringe on Mattel’s copyright, the jury will award damages.

The jury, which began deliberating Friday, had to determine whether Bryant made his original drawings while under contract with Mattel or while he was on vacation in his hometown of Missouri.

In the seven-week trial, Mattel has been fighting over ownership to the hip-hop inspired Bratz dolls, claiming Bryant took drawings of the Bratz line to competitor MGA after accepting a job at the company.

Analyst estimate Bratz generates $2 billion annually in worldwide licensing fees and revenue for privately held MGA.

Before the trial began, Mattel reached a confidential settlement with Bryant, who has earned more than $30 million in royalties from the Bratz line.

During the four-year legal battle, MGA has maintained that Mattel was merely trying to weed out the competition, and wanted some of the money from the popular brand. Since launching in 2001, the pouty fashion dolls have stolen a piece of Barbie’s market share.

In an April conference call to investors, Mattel Chief Financial Officer Kevin Farr said U.S. Barbie sales fell in the first quarter by 12 percent.